The expression prendre le maquis, meaning to join one of the armed guerrilla groups that took refuge in the French countryside, first appeared in late 1942. The development of the maquis is indissociable from the implementation of Compulsory Labour Service (STO), at the insistence of Fritz Sauckel, which was introduced by the law of 16 February 1943, replacing that of 4 September 1942, which had provided for the potential mobilisation of men aged 21 to 35. Prompting a strong reaction from the population, the promulgation of the STO and the call-ups and roundups that followed were quickly denounced by a flourishing underground press. On 1 March 1943, Libération had as its front-page headline ”French youth replies: Go to hell!” and called on its readers to: ”Sabotage the conscription of slaves for Hitler. [...] It amounts to the mass deportation of our youth.” Those who avoided the STO were often protected by friends or family willing to put them up. At least 10% of these ”STO dodgers”, possibly more, agreed to become maquisards, mostly out of patriotic instinct.